M - C dipole formation in fcc (face centred cubic) Fe 1-y M y C x solid solution (M = Ti,Nb)

Abstract

Available equilibrium carbon solubility data for fcc (face centred cubic) Fe_{1 - y}M_yC_x solid solution (M = Ti,Nb) reported as functions of temperature T and carbon activity a (C) were analysed taking into account the atomic interaction parameters derived through statistical thermodynamic analysis of related systems. In the fcc Fe_1-yM_yC_x under consideration, the affinity between C atom and M atom (M = Ti,Nb) is very much more attractive than that between C and Fe. Correspondingly, the atom configuration model in which M atoms are distributed randomly over the metal sub-lattice Fe_{1 - y}M_y and all the M atoms in the Fe_{1 - y}M_yC_x are bonded to C to form M - C dipoles was concluded to be the most realistic one reproducing the experimentally determined a (C) - T - x relationships at respective y.